A pilot model of a small size, mass, power, and cost, GaAs laser radar altimeter has been developed and tested for use over the ocean. Two versions have been developed, one for triggering a device at a predetermined altitude, and one for providing an altitude 'read out' as an analog dc voltage. Field tests from a bridge over an inland reservoir indicate performance with negligible false-alarm rate up to an altitude of 400 meters over the ocean, under all sea-state conditions, from glassy calm to the 'worst-case' rough sea state condition, and with the sun vertically overhead. A new remote sensing technique was developed to evaluate the roughness state of the water during field tests and to predict the mean laser return signal. This utilizes video imaging of the glitter pattern on the water from a bright point source light at night, or from the sun in the daytime. Tests of the altimeter over the ocean surface at sea are still needed, because extrapolation from ripples on the inland reservoir to full scale ocean waves is not fully understood. (rh)